Popular smoking articles, such as cigarettes, have a substantially cylindrical rod shaped structure and include a charge, roll or column of smokable material, such as shredded tobacco (e.g., in cut filler form), surrounded by a paper wrapper, thereby forming a so-called “smokable rod” or “tobacco rod.” Normally, a cigarette has a cylindrical filter element aligned in an end-to-end relationship with the tobacco rod. Typically, a filter element comprises plasticized cellulose acetate tow circumscribed by a paper material known as “plug wrap.” Certain filter elements can incorporate polyhydric alcohols. See, for example, UK Pat. Spec. 755,475. Certain cigarettes incorporate a filter element having multiple segments, and one of those segments can comprise activated charcoal particles. See, for example, U.S. Pat. Nos. 5,360,023 to Blakley et al. and 6,537,186 to Veluz. Typically, the filter element is attached to one end of the tobacco rod using a circumscribing wrapping material known as “tipping paper.” It also has become desirable to perforate the tipping material and plug wrap, in order to provide dilution of drawn mainstream smoke with ambient air. Descriptions of cigarettes and the various components thereof are set forth in Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) (1999). Certain types of cigarettes have possessed tobacco rods of relatively small circumference, such as those marketed commercially as “Capri” by Brown and Williamson Tobacco Corporation and “Virginia Slims Superslims” by Philip Morris Inc. See, for example, the types of cigarettes described in U.S. Pat. Nos. 4,637,410 to Luke; 4,878,507 to Case et al. and 4,911,184 to Case et al. A cigarette is employed by a smoker by lighting one end thereof and burning the tobacco rod. The smoker then receives mainstream smoke into his/her mouth by drawing on the opposite end (e.g., the filter end) of the cigarette.
There have been proposed numerous types of cigarettes, each of which has a rod composed of tobacco material configured such that a longitudinally extending central portion of that rod is formed as an air channel or is composed of a lesser amount of tobacco material than is used to provide the outer portion of that rod. U.S. Pat. No. 3,096,772 to Korber proposes a cigarette rod possessing tobacco filler formed so as to have a centrally located longitudinally extending air channel. U.S. Pat. No. 3,349,776 to Bell et al. proposes a cigarette having an outer region of tobacco surrounding a longitudinally extending column of a lower density. British Pat. No. 1,086,443 proposes a cigarette having a centrally extending cylindrical passage or a core whose density is less than the density of the surrounding outer layer. UK Pat. Spec. 1,054,557 and U.S. Pat. Nos. 4,632,130 to Heitmann et al. and 4,736,754 to Heitmann et al. each propose the manufacture of a cigarette rod having a central portion of smokable material of lesser density and an outer layer of smokable material of greater density.
There have been proposed numerous types of cigarettes, each of which has an axial inner zone of smokable material of a constitution different from that of a smokable material that is disposed outside of that zone. U.S. Pat. No. 1,829,559 to Gilliam proposes a cigarette having a paper wrapper and filler composed of different species of tobacco, and each species is disposed in a separate stratum or layer throughout the entire length of the cigarette. U.S. Pat. Nos. 3,736,941 to Molins et al.; 3,957,062; 3,987,804 to Molins et al.; and 4,207,906 to Seehofer et al.; and UK Pat. Spec. 1,416,020 propose manufacturing a cigarette rod having a core of filler material different from an annulus of shredded tobacco. U.S. Pat. Nos. 4,580,579 to Wahle et al. and 4,593,704 to Wahle et al. each propose equipment and methods for producing a rod of tobacco filler having a core containing a first particulate material surrounded by an annular envelope containing a different second particulate material. U.S. Pat. No. 4,716,913 to Brackmann proposes a cigarette having a core of lesser quality tobacco smoking material surrounded by an annulus of higher quality smoking material.
There have been proposed numerous types of cigarettes, each of which has an inner zone of smokable material contained within a wrapper and an outer zone of smokable material that is disposed outside of that zone. U.S. Pat. No. 3,910,287 to Walton proposes a cigarette-type smoking device having inner and outer wrappers of cigarette paper or reconstituted tobacco, with the space within the inner wrapper defining the major volume of the device and the principal tobacco-filled combustion zone, while the space between the wrappers defines a minor volume and a secondary tobacco-filled combustion zone. A so-called “coaxial cigarette” possesses an inner core of tobacco material, a sheath for the inner core, an outer jacket of material coaxially surrounding the inner core and sheath, and a sheath for the outer jacket. See, for example, U.S. Pat. No. 4,986,287 to Schneider et al. U.S. Pat. No. 4,874,004 to Borowski et al. proposes a coaxial cigarette having an inner core of a smokable material, a first wrapper for the inner core, an outer jacket of another smokable material surrounding the inner core, and a second wrapper for the outer jacket. U.S. Pat. No. 6,257,243 to Muller et al. proposes a coaxial cigarette possessing an inner segment of smokable material, a covering for the inner segment, an outer segment of tobacco material surrounding the inner segment, and a covering for the outer segment. PCT WO 98/57556 to Biggs et al. proposes a coaxial cigarette possessing an inner segment of tobacco material, a wrapper for the inner segment, an outer segment of smokable material surrounding the inner segment, and a covering for the outer segment. U.S. Pat. No. 4,727,888 to Luke proposes manufacturing a cigarette rod by surrounding a rod of filler material wrapped in a wrapper material with a smoking material, and wrapping a wrapper material about the smoking material. U.S. Pat. Nos. 3,987,804 to Molins et al. and 6,202,648 to Schumacher et al. each propose equipment and methods for manufacturing a cigarette rod having a tubular insert that is surrounded by a smokable material.
Other types of coaxial or concentric-type smoking articles have been proposed. Certain proposed cigarette-type smoking articles have possessed tobacco smokable materials surrounding longitudinally extending cores of other materials. UK Pat. Application 2,070,409 proposes smoking article having a rod of smoking material having at least one filament extending over a least a major portion of the length of the rod. U.S. Pat. No. 3,614,956 to Thornton proposes a smoking article having an annular outer portion made of tobacco smoking material and a central cylindrical core of absorbent material. U.S. Pat. No. 4,219,031 to Rainer et al. proposes a smoking article having a central core of carbonized fibers circumscribed by tobacco. U.S. Pat. No. 6,367,481 to Nichols et al. proposes a cigarette possessing an ignition element surrounded by tobacco, which is in turn surrounded by a composite outer wrapper. One type of cigarette-type smoking article has possessed a rod of tobacco smokable material surrounded a longitudinally extending annulus of some other material. U.S. Pat. No. 5,105,838 to White et al. proposes a rod of smokable material, normally circumscribed by a layer of wrapping materials, which is in turn circumscribed by an insulating material (e.g., glass fibers). PCT WO 98/16125 to Snaidr et al. proposes a smoking device constructed from a very thin cigarette designed to fit into a tubular ceramic cartridge.
Through the years, there have been proposed various methods for altering the composition of mainstream tobacco smoke. In PCT WO 02/37990 to Bereman, it has been suggested that metallic particles and/or carbonaceous particles can be incorporated into the smokable material of a cigarette in an attempt to reduce the amounts of certain compounds in the smoke produced by that cigarette. In addition, numerous tobacco substitute materials have been proposed, and substantial listings of various types of those materials can be found in U.S. Pat. Nos. 4,079,742 to Rainer et al. and 4,771,795 to White et al. Certain cigarette-type products that employ non-tobacco materials (e.g., dried vegetable leaves, such lettuce leaves) as filler that is burned to produce smoke that resembles tobacco smoke have been marketed under the tradenames “Cubebs,” “Triumph,” “Jazz,” and “Bravo.” See, for example, the types of materials described in U.S. Pat. No. 4,700,727 to Torigian. Furthermore, tobacco substitute materials having the tradenames “Cytrel” and “NSM” were introduced in Europe during the 1970s. Representative types of proposed synthetic tobacco substitute materials, and cigarettes incorporating those materials, are described in British Pat. No. 1,431,045; and U.S. Pat. Nos. 3,738,374 to Bennett; 3,844,294 to Webster; 3,878,850 to Gibson et al.; 3,931,824 to Miano et al.; 3,943,941 to Boyd et al.; 4,044,777 to Boyd et al.; 4,233,993 to Miano et al.; 4,286,604 to Ehretsmann et al.; 4,326,544 to Hardwick et al.; 5,046,514 to Bolt; 5,074,321 to Gentry et al.; 5,092,352 to Montoya et al.; 5,778,899 to Saito et al.; 6,397,852 to McAdam; and 6,408,856 to McAdam. Various types of highly processed smokable materials incorporating tobacco and other ingredients are set forth in U.S. Pat. Nos. 4,874,000 to Tamol et al.; 5,072,744 to Luke et al.; 5,829,453 to White et al. and 6,182,670 to White et al.
Numerous references have proposed various smoking articles of a type that generate flavored vapor, visible aerosol, or a mixture of flavored vapor and visible aerosol. Some of those proposed types of smoking articles possess tubular sections or longitudinally extending air passageways. See, for example, those types of smoking articles described in U.S. Pat. Nos. 3,258,015 to Ellis et al.; 3,356,094 to Ellis et al.; 3,516,417 to Moses; 4,347,855 to Lanzellotti et al.; 4,340,072 to Bolt et al.; 4,391,285 to Burnett et al.; 4,917,121 to Riehl et al.; 4,924,886 to Litzinger; and 5,060,676 to Hearn et al. Many of those types of smoking articles have employed a combustible fuel source that is burned to provide an aerosol and/or to heat an aerosol forming material. See, for example, the background art cited in U.S. Pat. Nos. 4,714,082 to Banerjee et al. and 4,771,795 to White et al.; which are incorporated herein by reference in their entireties. See, also, for example, those types of smoking articles described in U.S. Pat. Nos. 4,714,082 to Banerjee et al.; 4,771,795 to White et al.; 4,793,365 to Sensabaugh; 4,917,128 to Clearman et al.; 4,961,438 to Korte; 4,966,171 to Serrano et al.; 5,033,483 to Clearman et al.; 5,065,776 to Lawson; 5,099,861 to Clearman et al.; 5,105,835 to Drewett et al.; 5,159,940 to Hayward et al.; 5,178,167 to Riggs et al.; 5,183,062 to Clearman et al.; 5,211,684 to Shannon et al.; 5,551,451 to Riggs et al.; 5,595,577 to Bensalem et al.; 5,819,751 to Barnes et al.; 6,095,153 to Beven et al; 6,578,584 Beven; and PCT WO 97/48294. Furthermore, certain types of cigarettes have been commercially marketed under the brand names “Premier” and “Eclipse” by R. J. Reynolds Tobacco Company. See, for example, those types of cigarettes described in Chemical and Biological Studies on New Cigarette Prototypes that Heat Instead of Burn Tobacco, R. J. Reynolds Tobacco Company Monograph (1988) and Inhalation Toxicology, 12:5, p. 1-58 (2000).
Yet other types of smoking articles, such as those types of smoking articles that generate flavored vapors by subjecting tobacco or processed tobaccos to heat produced from chemical or electrical heat sources are described in U.S. Pat. Nos. 4,947,874 to Brooks et al.; 5,224,498 to Deevi; 5,285,798 to Banerjee et al.; 5,357,984 to Farrier et al.; 5,593,792 to Farrier et al.; 5,369,723 to Counts; and 6,164,287 to White. One type of smoking article that has employed electrical energy to produce heat has been commercially marketed by Philip Morris Inc. under the brand name “Accord.”
Smoking articles that employ tobacco substitute materials, and smoking articles that employ sources of heat other than tobacco cut filler to produce tobacco-flavored vapors or tobacco-flavored visible aerosols, have not received widespread commercial success. It would be highly desirable to provide a smoking article, such as a cigarette, that possesses the ability to provide to a smoker the benefits and advantages of conventional cigarette smoking without delivering considerable quantities of incomplete combustion and pyrolysis products.